Net Metering or Reverse Metering is a type of billing system that pays off the customer and reduces the monthly electricity bill. An On-Grid system allows anyone to sell the surplus energy generated from his/her own installed solar powered system and get paid by the local utility company. It works on the principle of a bi-directional rotating meter if your house needs more electricity units than usual you can borrow (buy) them from the utility grid and if your installed system generates more electricity units, you can lend (sell) them to the utility grid and charge the company instead.